U.S. Pat. No. 4,461,688 teaches a sputtering cathode with a plate-shaped target and a plurality of U-shaped magnetic units located on the surface of the target facing away from the substrate. The front surfaces of the two legs of a first U-shaped magnetic unit lie close to the edges of the averted surface of the target, the front surfaces of the legs of a second pair of U-shaped magnetic units lie close to one half of the averted surface of the target, and the front surfaces of the two legs of additional pairs of smaller U-shaped magnetic units lie close to the external half of a portion of the averted surface of the target, which portion is overlapped by the second pair of magnetic units. This patent is incorporated herein by reference in its entirety.
A sputtering cathode is taught in U.S. Pat. No. 4,265,729 having magnets on the surface of the target facing away from the substrate which form a magnetic field, the bodies of the magnets being right prisms. The base edges are inclined with respect to the plane of the target, with the lines of force of the magnets running parallel to the flat edges, standing upright at the ends of the bodies. This patent is also incorporated herein by reference in its entirety.